Answer 2:
What you saw was an aurora borealis (in
the southern counterpart it is called aurora
australis). It is interesting that we see the
aurora close to the north and south pole here on
Earth, but the aurorae actually starts at the
center of the solar system.
The Sun is constantly
blowing out a stream of protons and electrons,
called the Solar Wind. It takes about three
days for those particles to get near the earth and
interact with the Earth's magnetic field. You can
think of the Earth's magnetic field as coming out
of the ground at the north pole, going around the
earth from north to south, and then going back in
at the south pole.
The particles that hit the
magnetic field want to 'slide down' the field to
the poles. When they do this, they eventually hit
the earth's atmosphere. These particles are moving
very fast, and when they hit the air they slam
into air atoms that make up our atmosphere,
sometimes knocking loose more electrons. After a
short time these free electrons get back together
with their parent atoms, and when they do, the
atoms give off light. This light is usually
greenish, but is sometimes red as well (it depends
on what kind of atom you have). When this
happens to lots of atoms, you get lots of
light--the aurorae. The amount of energy involved can
sometimes be more than the entire United States
uses!
From Philip Plait, Astronomer who answered that
question
at:
here.
Click Here to return to the search form.
| 
